Mobile communication networks are ubiquitous in many parts of the world. Third- and fourth-generation mobile networks utilize Radio Frequency (RF) transmissions in a Radio Access Network (RAN) to effect voice and data communications between geographically dispersed network nodes (Base Stations or BSs) and a large number of mobile communication terminals (Mobile Terminals, or MTs). In order to successfully transmit data between MTs and their serving BSs, radio resources are assigned to the communication links in both downlink (BS to MT) and uplink (MT to BS) directions. Power, times slots and frequency segments are examples of scarce radio resources available at the radio interface. Radio Resource Allocation (RRA) is a key functionality of mobile networks since it is responsible for the management of the scarce resources available in the radio access part of the mobile networks.
In addition to the physical limitation of the available resources, the demand for higher data rates is continuously increasing, motivated by new service applications and mobile devices such as smartphones and tablets. Mobile network operators should therefore be capable of providing sustainable levels of Quality of Service (QoS) to different service applications with heterogeneous requirements. In this context, efficient RRA is highly desired.
The 3rd Generation Partnership Project (3GPP), a wireless communication standards body, has chosen Single Carrier-Frequency Division Multiple Access (SC-FDMA) as the multiple access technology for the uplink of Long Term Evolution (LTE) networks. One reason for adopting SC-FDMA is its property of controlling Peak-to-Average Power Ratio (PAPR). Signals with high PAPR place a significant burden on MTs, due to the need for highly linear power amplifiers to avoid excessive signal distortion. For more information, see the paper by H. G. Myung, J. Lim, and D. J. Goodman, titled “Single Carrier FDMA for Uplink Wireless Transmission,” published in IEEE Vehicular Technology Magazine, vol. 1, no. 3, pp. 30-38, September 2006, the disclosure of which is incorporated herein by reference in its entirety.
The SC-FDMA multiple access scheme imposes two constraints on resource assignment: exclusivity and adjacency. With the exclusivity constraint, a given frequency resource—such as a set of one or more adjacent OFDM subcarriers—should not be shared by multiple MTs within a cell. In other words, each frequency resource should be assigned to at most one MT within a cell to prevent intra-cell interference. In the adjacency constraint, if multiple frequency resource blocks are allocated to a given MT for transmission, they should all be adjacent in the frequency domain, so as to obtain benefits in terms of PAPR. The adjacency constraint significantly reduces the freedom in RRA compared to other multiple access schemes.
Mobile network operators measure system performance in general by means of minimum user satisfaction constraints for each provided service type. More specifically, system operators require that a certain fraction of the connected MTs of each service be satisfied with the provided QoS—referred to herein as the minimum service requirement constraint for each service. For more information, see the paper by F. R. M. Lima, S. Wänstedt, F. R. P. Cavalcanti, and W. C. Freitas, titled “Scheduling for Improving System Capacity in Multiservice 3GPP LTE,” published in Journal of Electrical and Computer Engineering, no. 819729, 2010, the disclosure of which is incorporated herein by reference in its entirety. In particular, a need exists in the art to perform efficient RRA that fulfills the minimum satisfaction guarantees for each provided service in the uplink of SC-FDMA systems.
The Background section of this document is provided to place embodiments of the present invention in technological and operational context, to assist those of skill in the art in understanding their scope and utility. Unless explicitly identified as such, no statement herein is admitted to be prior art merely by its inclusion in the Background section.